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2409.19393

Extravagance, irrationality and Diophantine approximation

Jon. Aaronson, Hitoshi Nakada

correctmedium confidence
Category
math.DS
Journal tier
Strong Field
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper proves all claimed results with precise hypotheses and rigorous arguments: (i) Bugeaud’s lemma and Denominator/approximation estimates; (ii) an extravagance dichotomy under continued-fraction mixing; (iii) existence of Gauss-invariant ergodic measures with prescribed irrationality exponent; and (iv) a Khinchin-type dichotomy for weak Rényi measures doubling at 0. By contrast, the model’s outline contains critical missteps: (A) a misapplied Borel–Cantelli/Markov bound leading to an unjustified conclusion Y_{n+1}=o(n) in the integrable case, and (B) an unproven uniform comparability of µ(U_q) from 'doubling at 0' plus weak Rényi, and an application of the weak-Rényi Borel–Cantelli lemma to sets not lying in the required σ-field. The conclusions match the paper, but the model’s proof outline is not correct as written.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The work gives a clear and robust framework connecting extravagance of stationary processes to metric Diophantine approximation for Gauss-invariant measures, with sharp dichotomies and constructive existence results. The techniques (CF-mixing and weak Rényi Borel–Cantelli) are applied carefully. Minor additions to exposition would further aid readers.